The development of insulin resistance and anabolic resistance during muscle disuse: what is the role of fuel integration? (360G-Wellcome-209198_Z_17_Z)

Skeletal muscle atrophy, which occurs during short-term disuse, is thought to be due to the development of anabolic resistance of protein metabolism and insulin resistance of glucose metabolism, although their cause is currently unknown. The primary research aim of this fellowship is to establish the role of muscle fuel availability and integration in disuse-induced insulin and anabolic resistance. In collaboration with the Medical School, I will perform two randomized, placebo-controlled studies in which young, healthy participants undergo 2 days of forearm immobilisation with placebo, Acipimox (to decrease plasma lipid availability), Formoterol (to stimulate glycolytic flux), or dietary branched-chain amino acid (BCAA) manipulation, to alter substrate availability. I will combine the arteriovenous-venous forearm balance technique, that I have recently established in Exeter, with stable isotope amino acid infusion and repeated forearm muscle biopsies to quantify muscle glucose, fatty acid, and BCAA balance, oxidation, and intermediary metabolism (including muscle protein synthesis), both fasted and during a hyperinsulinaemic-euglycaemic-hyperaminoacidaemic clamp. Two periods of research at the University of Texas Medical Branch will enable me to develop skills in mass spectrometry tracer analyses and develop a network of collaborators in the USA, both crucial for my future career investigating disuse-induced muscle atrophy.